Assessment of Soil Degradation under Different Land Use Practices in Owerri, Imo State, Southeastern Nigeria: Implications for Sustainable Agricultural Development

Soil degradation is a critical constraint to sustainable agricultural development, particularly in rapidly urbanizing regions of sub-Saharan Africa. This study assessed the extent of soil degradation under four land use types: oil palm plantation (OP), secondary forest (SF), industrial layout (IL), and residential layout (RL), in Owerri, Imo State, Southeastern Nigeria. Eight profile pits were dug, and 37 soil samples were collected through genetic horizons and analyzed for physical and chemical properties; and degradation indices, including dispersion ratio (DR), clay dispersion ratio (CDR), clay flocculation index (CFI), clay dispersion index (CDI), structural stability index (S), exchangeable sodium percentage (ESP), sodium adsorption ratio (SAR), and soil degradation rating (SDR). Results showed that IL soils exhibited the highest DR (0.68–0.71), lowest S (0.22–0.29), highest BD (1.64–1.70 Mg m⁻³), and lowest SOC (0.34–0.39 g/kg), classifying IL I as severely degraded (mean RWF = 4). SF soils consistently outperformed other land uses in structural stability (S = 0.69–0.72), SOC content (1.00–1.01 g/kg), and TN (47–48%). RL soils were moderately degraded but showed worrying compaction trends (BD up to 1.73 Mg m⁻³). All ESP (2.11–4.33%) and SAR (0.11–0.49) values were below sodicity thresholds, although variability was high for some indicators (CV > 30%). Integration of statistical and graphical outputs revealed that IL and RL land uses are the primary drivers of degradation in the area. Management interventions should prioritize organic matter enhancement, erosion control, and land use planning to prevent further decline in soil quality and maintain agricultural productivity. This study provides baseline data to guide sustainable soil management policies in Southeastern Nigeria and similar agro-ecological zones.